security group error

2016-09-19 21:25:04.567 23954 INFO vmware_dvs.agent.firewalls.dvs_securitygroup_rpc [req-130af5d9-0bcd-411b-b32f-7c72ba07874f - - - - -] Preparing filters for devices set([8fbd3ccd-8ded-4e2a-93f9-c0c3d3d818e2, 688c4734-d972-4129-ade2-4f187003c91b])
2016-09-19 21:25:04.640 23954 INFO vmware_dvs.agent.firewalls.vcenter_firewall [req-130af5d9-0bcd-411b-b32f-7c72ba07874f - - - - -] Set security group rules for ports [u'8fbd3ccd-8ded-4e2a-93f9-c0c3d3d818e2', u'688c4734-d972-4129-ade2-4f187003c91b']
2016-09-19 21:25:04.699 23954 CRITICAL neutron [req-130af5d9-0bcd-411b-b32f-7c72ba07874f - - - - -] AttributeError: 'NoneType' object has no attribute 'get_port_info'
2016-09-19 21:25:04.699 23954 ERROR neutron Traceback (most recent call last):
2016-09-19 21:25:04.699 23954 ERROR neutron   File "/usr/bin/neutron-dvs-agent", line 10, in <module>
2016-09-19 21:25:04.699 23954 ERROR neutron     sys.exit(main())
2016-09-19 21:25:04.699 23954 ERROR neutron   File "/usr/lib/python2.7/site-packages/vmware_dvs/agent/dvs_neutron_agent.py", line 431, in main
2016-09-19 21:25:04.699 23954 ERROR neutron     agent.daemon_loop()
2016-09-19 21:25:04.699 23954 ERROR neutron   File "/usr/lib/python2.7/site-packages/vmware_dvs/agent/dvs_neutron_agent.py", line 297, in daemon_loop
2016-09-19 21:25:04.699 23954 ERROR neutron     self.rpc_loop(polling_manager=pm)
2016-09-19 21:25:04.699 23954 ERROR neutron   File "/usr/lib/python2.7/site-packages/vmware_dvs/agent/dvs_neutron_agent.py", line 318, in rpc_loop
2016-09-19 21:25:04.699 23954 ERROR neutron     self.process_ports()
2016-09-19 21:25:04.699 23954 ERROR neutron   File "/usr/lib/python2.7/site-packages/vmware_dvs/agent/dvs_neutron_agent.py", line 359, in process_ports
2016-09-19 21:25:04.699 23954 ERROR neutron     upd_ports)
2016-09-19 21:25:04.699 23954 ERROR neutron   File "/usr/lib/python2.7/site-packages/neutron/agent/securitygroups_rpc.py", line 286, in setup_port_filters
2016-09-19 21:25:04.699 23954 ERROR neutron     self.prepare_devices_filter(new_devices)
2016-09-19 21:25:04.699 23954 ERROR neutron   File "/usr/lib/python2.7/site-packages/vmware_dvs/agent/firewalls/dvs_securitygroup_rpc.py", line 48, in prepare_devices_filter
2016-09-19 21:25:04.699 23954 ERROR neutron     self.firewall.prepare_port_filter(devices.values())
2016-09-19 21:25:04.699 23954 ERROR neutron   File "/usr/lib/python2.7/site-packages/vmware_dvs/agent/firewalls/vcenter_firewall.py", line 182, in prepare_port_filter
2016-09-19 21:25:04.699 23954 ERROR neutron     self._process_port_filter(ports)
2016-09-19 21:25:04.699 23954 ERROR neutron   File "/usr/lib/python2.7/site-packages/vmware_dvs/agent/firewalls/vcenter_firewall.py", line 202, in _process_port_filter
2016-09-19 21:25:04.699 23954 ERROR neutron     port_info = port_dvs.get_port_info(port)
2016-09-19 21:25:04.699 23954 ERROR neutron AttributeError: 'NoneType' object has no attribute 'get_port_info'
2016-09-19 21:25:04.699 23954 ERROR neutron